1. Field of the Invention
This invention relates to a new and improved bottle cap. More particularly, the present invention is directed to a bottle cap having an improved sealing bead configured to engage a container crown proximal the maximum diameter thereof. The present invention is also directed to a bottle cap having an improved tear tab including a line of weakness extending along a skirt upward from a bottom edge of the bottle cap and onto a top of the bottle cap. The present invention is also directed to a bottle cap having a liner retainer.
2. Description of Related Art
An exemplar of a known cap for use with large water containers of the type used with water dispensers and water coolers is U.S. Pat. No. 5,232,125 to Adams. The cap disclosed by the Adams '125 patent includes a top, a cylindrical side wall extending downward from the top, a rounded corner interconnecting the top and the cylindrical side walls, and a tension ring configured to fit under the neck bead, that is a crown of a container neck. The cap disclosed by the Adams '125 patent also includes internal upper and lower seal beads on the inside of the wall of the corner which are configured to tightly engage the container lip and seal against leakage.
The large water containers used with such known caps are generally blow molded and include neck finishes that are trimmed or otherwise finished using conventional methods. Although the neck finishes are somewhat standardized within the container industry, the actual heights of container neck crowns tend to vary to some degree due to the trimming and other finishing processes. In the event that excessive material is removed from a container neck crown during trimming, the upper and lower seal beads of known caps of the type disclosed by the Adams '125 patent might not effectively seal against the crown.
Caps of the type disclosed by the Adams '125 patent generally include a score line having a curved portion which extends from the base of the cap skirt to a horizontal portion. Although such score lines are effective for removing the cap from a container, a substantially vertical score line is beneficial for manufacturing purposes because caps molded with vertical score lines are generally easier to uniformly fill with molten resin and easier to remove from a mold. Due to the substantial skirt height of such caps, a single vertical score line of the type generally used on shorter caps, such as those disclosed by U.S. Pat. No. 6,082,567 to Bietzer et al., is generally insufficient to remove a cap from a large water container. Instead, a pair of vertical tear lines is needed to facilitate removal of the cap from a container.
An exemplar of a cap having a pair of vertical tear lines is U.S. Pat. No. 6,102,226 to Verderber which shows a bottle cap having a top, a skirt, a tab, and vertical tear lines which extend from the tear tab and terminate on an upper portion of the skirt below the top. The Verderber patent also discloses a bottle cap having a top, a skirt, a tab, and a single vertical tear line which extends downward from a circumferentially extending, horizontal internal tear line. The Verderber patent discloses yet another bottle cap including a top, a skirt, a tab, and a single vertical tear line which extends around the top at the intersection of a bevel and the top.
U.S. Pat. No. 6,177,041 to Bietzer shows another cap having a top, a skirt, a tear tab, and vertical tear lines which extend from the tear tab and terminate on an upper portion of the skirt. One of the tear lines disclosed by Bietzer extends close to the top while the other tear line terminates at a location somewhat below the top.
U.S. Pat. No. 5,909,827 to Bietzer et al. shows a cap having a top, a skirt, and vertical score lines which extend from the tear tab. One score line extends up to an upper slanted portion of the skirt. The other score line extends from up the bottom of the skirt to the top.
Although conventional wisdom might imply that extending both tear lines to the top of a cap would be beneficial for removing the cap from a container, the prior art shows at least one tear line of a cap generally terminating at a location somewhat below the top in order to facilitate removal of the cap from the bottle. As described in the Bietzer '041 patent, it was found that pulling on the tab of caps having a pair of tear lines which extend to the top thereof actually caused a locking ring thereof to increase its grip on a bottle used therewith thus making the cap very hard to remove. In particular, pulling the tab of such caps causes a reduction in the effective diameter of the locking ring disadvantageously tightening the locking ring around the bottle. Thus, a user frequently needed to grip the skirt of such caps and pry them from the bottle.
Furthermore, removal of known caps generally does not completely fracture and/or destroy all sealing means of the caps. Accordingly, users of known caps may be inclined to misuse the caps by reusing the caps on a reusable bottle. Storage of potentially dangerous substances is a major concern in the field of reusable bottles.
One aspect of many closures for bulk water containers is that they include a form of liner to increase the integrity of the seal. One common form of liner comprises a plastic, highly compressible foam. Because they are highly compressible, these liners are able to accommodate a wide range of bottle dimensions and common bottle finish defects. These plastic foam liners are most often cut as a disk or annular “donut” from a sheet of material and then inserted or punched into the closure or bottle cap. The disk or “donut” is cut to a diameter larger than an inside diameter of the closure locking bead of the cap and this diametrical interference suffices to retain the liner in the cap during transport and application to the container or bottle without having to resort to more expensive retention processing such as hot melt gluing.
A characteristic of the plastic foam liner systems is that the only retention mechanism holding the liner within the cap is the above-mentioned diametrical interference between the liner and the closure locking bead of the cap. In this case, a certain amount of liner shifting can occur for various reasons. Firstly, during mechanical cutting and insertion processes, the liner might not be inserted perfectly axially with respect to the cap. Secondly, during application of the closure to a container neck, a certain amount of cap distortion and/or cocking, that is tilting or slanting, with respect to the container neck may occur. In other words, a first portion of the perimeter of the closure may seat on the container neck prior to another portion circumferentially removed from the first portion. This “cocking” action can “pull” the liner in the direction of the first portion thus shifting the liner with respect to the container and the closure. Finally, the forces involved in the vertical application of the closure to a plastic container generally cause some axial compression of the plastic container, resulting in escape of some of the air in the headspace above the liquid within the container. The flow of this air outward through the neck of the container can cause the liner to shift with respect to both the container and the closure.
In the past, the diameter of the liners used has been sufficient to accommodate the above described shifting while still ensuring that the liner contacts the crown sealing surface of a conventional blown-finish container around its full circumference. More recently, however, alternate manufacturing techniques have emerged which make it desirable to increase the internal diameter of the container neck bore. Specifically, crown finishes of the container neck formed by injection molding or compression molding place a premium on increasing the internal diameter of the bore in order to save material and reduce manufacturing cycles. In addition, increased bore diameters decrease the possibility of damaging the top finish of the container neck from incidental contact with fill tubes of container filling equipment.
Disadvantageously, increasing the bore diameter of a container neck decreases the top “land” area of the crown finish. A cross-sectional comparison of the land areas for a conventional blown finish versus the more recent injected or compression finishes is shown in FIGS. 13 and 14. In FIGS. 13 and 14, the “land” surface or area of the two different types of finishes are indicated by L1 and L2, respectively.
It has now been observed that the above described liner shifting may be sufficient to cause the liner to miss the reduced land area L2 presented by bottles having increased bore size, as shown in FIG. 14, resulting in inadequate sealing and leakage.
What is needed is a cap which overcomes the above and other disadvantages of known caps.